Door latch mechanism



J. S. FOX, SR

DOOR LATCH MECHANISM Feb. 6, 1968 2Sheets-Sheet 1 Filed March 10, 1966F'IGZ H s ATTORNEY Feb. 6, 1968 J 5. FOX, SR 3,367,697

I DOOR LATCH MECHANISM Filed March 10, 1966 2 Sheets-Sheet 2 6 FIGS I v4. INVENTOR.

TOSEPH 3. Fox, 5'2.

ms- ATTORNEY United States Patent ()flice 3,367,697 DOOR LATCH MECHANISMJoseph S. Fox, Sr., Louisville, Ky., assignor to General ElectricCompany, a corporation of New York Filed Mar. 10, 1966, Ser. No. 533,3446 Claims. (Cl. 292-413) ABSTRACT OF THE DISCLOSURE A door latch mechnismas for use with a kitchen appliance such as a self-cleaning baking ovenor an automatic dishwasher where the mechanism includes a supportingbracket having a pivoted latching bolt and a pivoted handle leverconnected thereto by means of a cam follower arrangement to give thelatching bolt both a swinging and a lineal movement to pull the door intight. Also pivoted to the bracket and generally coinciding and movingwith the latching bolt is a door sensor bar that serves to interrupt theclosing action of the latch mechanism if the door is not present in itsclosed position. The door sensor bar is adapted to be deflected aside bythe presence of the door so that the latching bolt may complete itstravel to the fully closed position.

The present invention relates to a door latch mechanism for holding adoor in a tightly locked position. Such doors are sometimes referred toas a self-sealing type; i.e., doors having latches which are so designedthat during the final stages of their closing movement they causecompression of a door gasket.

This invention is an improvement over the door latch mechanism ofLetters Patent 3,189,375 issued to Clarence Getman on June 15, 1965, andassigned to the General Electric Company, the assignee of the presentinvention. Both of these door latch mechanisms were developed for usewith a high temperature oven for domestic use where the oven hasprovision for an automatic heat cleaning cycle during which thetemperature is raised to between about 750 F. and about 950 F. so as todecompose all food soil from the oven liner Walls. With such highoperating temperatures it is imperative to latch the oven door beforethe cleaning cycle is set in motion so that the door can not be openedduring the heat cleaning cycle. It is likewise important to seal thedoor so as to preclude the escape of smoke, odor and heat from aroundthe door while the food soil is being removed from the oven liner wallsby a process of pyrolysis. If it were possible to open the door whilethe oven was operating at these elevated heat cleaning temperatures,there would be a sudden inrush of oxygen into the oven cavity to combinewith the hot gases and this might cause a sudden high flame which couldbe harmful. Accordingly, door latches and oven controls have beendevised which prevent the initiation of the heat cleaning cycle untilthe door latch mechanism has clamped the door into a sealed position,and they prevent the door from being re-opened until the temperaturewithin the oven drops to a level below the maximum normal cookingtemperature of about 550 F.

The primary object of the present invention is to provide a simplifieddoor latch mechanism having an improved door sensing means to insurethat the door latch mechanism cannot be closed it the door is not firstpresent in its closed position.

Another object of the present invention is to provide such a door latchmechanism which is constructed from a minimum number of parts that areeasy to assemble and reliable in operation.

The present invention, in accordance with one form thereof, is embodiedin a door latch mechanism including 3,361,697 Patented Feb. 6, 1968 abracket mounted within a door frame adjacent the distal edge of thedoor. The bracket includes a flange portion disposed adjacent an openingin the door frame. A latching bolt is pivotally mounted on the bracketand adapted to engage and disengage the door to be locked. A handlelever is also pivotally mounted to the bracket and connected to thelatching bolt by a cam follower arrangement so that swinging movement ofthe handle causes first a comparable swinging movement of the latchingbolt to engage the door and then a substantially lineal movement towardthe door frame by the latching bolt to compress the door gasket. Theflange portion has an opening therein through which the latching bar ismoved by the handle lever. A door sensor bar is pivotally supported onthe latching bolt for movement therewith and includes a hook portionwhich will engage the flange so that the handle cannot be moved to itsfully closed position unless the door sensor bar has first beendeflected by the presence of the door. If the door is moved to andretained in its closed position prior to the closing movement of thehandle lever, the door sensor bar will be deflected by the door so thatits hook portion will not engage the bracket flange and the latchingbolt will be free to fully close and lock the door.

My invention will be better understod from the following descriptiontaken in conjunction with the accompanying drawings and its scope willbe pointed out in the appended claims.

FIGURE 1 is a right side elevational view of a freestanding range havinga door latch mechanism embodying the present invention;

FIGURE 2 is a fragmentary plan view, partly in cross section on anenlarged scale, taken along line 2-2 of FIGURE 1 and shows the latchmechanism in its open position disengaged from the oven door, whichwould be the position of the latch mechanism during normal cookingoperations;

FIGURE 3 is a fragmentary plan view similar to FIG- URE 2 showing theoven door in its closed position and the latch mechanism moved to itsfully closed position;

FIGURE 4 is a fragmentary plan view similar to that of FIGURE 2illustrating the situation when the door has been left open and thehandle lever has been moved toward its closed position until the hookportion of the door sensor bar has engaged the flange of the latchmechanism bracket; and

FIGURE 5 is a fragmentary elevational view taken along the line 5-5 ofFIGURE 3.

Turning now to a consideration of the drawings and particularly toFIGURE 1, there is shown for illustrative purposes a freestandingelectric range 10 having a top cooking surface 11 with a plurality ofsurface heating elements 12, and oven cavity 13, a front-opening ovendoor 14, and a backsplasher 15 arranged along the back edge of thecooking surface 11 and containing a control panel (not shown) havingcontrol components which govern the energization of the various heatingelements of the range. The oven cavity 13 includes two standard electricheating elements; namely, a lower bake unit 16 arranged just above thebottom of the oven cavity and an upper broil unit 17 which is locatedjust under the top wall of the oven cavity.

The latch mechanism of the present invention is indicated by the numeral20 and is located within the oven cabinet or range body above the dooropening. As mentioned previously, this invention of a new and improvedlatch mechanism 20 has been found of primary importance when used with ahigh temperature heat cleaning oven. In such an oven there is a thirdheating element or mullion heater 21, as seen in FIGURE 5, that islocated near the front of the door opening of the oven cavity toencircle the oven liner and compensate for the loss of heat through andaround the door. It is a type of heating element that has a helicalresistance wire encased in a high temperature insulating material suchas magnesium oxide, and which in turn is covered with a metal sheath orjacket, as is standard heating element construction in this art.

In designing oven door arrangements for ranges there is a decidedadvantage in placing the door latch mechanism in the range body or doorframe rather than in the door structure. When the latch mechanism is inthe range body it can be mounted above the oven insulation 22 so that issomewhat protected from the high temperature of the oven liner 23 whichforms, with the oven door 14, the oven cavity 13. The oven door is of arelatively thin construction and would provide little heat protectionfor the latch as compared with the available insulated space under thetop cooking surface 11. It is recognized that in other applications,such as drop-door automatic dishwashers, the parts could be reversed soas to locate the latch mechanism in the door without departing from thespirit of the present invention.

Referring now particularly to FIGURES 2-5, the latch mechanism is shownas comprising a mounting bracket 25 which is a generally fiat sheetmetal member with an upturned flange 26 along its front edge so that itmay be screwed to the rear surface of the front wall of the range body.A pin 28 extends from bracket 25 and is received in an elongated slot 29formed in a latching bolt 30. Thus, the latching bolt 30 may pivot aboutpin 28 for a swinging type motion as Well as slide around pin 28 for asubstantially lineal type motion. The forward end of the latching bolt30 has a hook portion 31 which is adapted to engage a keeper 32 on theoven door 14. The front wall of the range body has an elongated slot oropening 33 and a portion of the flange 26 overlies the slot or opening.The flange 26 is formed with an opening or slot 34 in communication withthe slot 33 and arranged for receiving the latching bolt 30therethrough. The oven door 14 has a similar slot 35 formed in its innerdoor liner and is hollow in the vicinity of this slot 35 to permit thehook portion 31 of the latching bolt to extend into the interior of thedoor and engage around the side edge of keeper 32. A modified doordesign could use a cantilever spring within the door for engagement bythe book 31 so as to compensate for manufacturing tolerances and allowthe use of a more rigid gasket construction.

A handle lever 36 is pivotally mounted on the rearward portion ofmounting bracket 25 by means of a pivot pin 37. The outer end of handlelever 36 extends outwardly between the top of door 14 and the lower sideof cooking surface 11 and is formed with a knob or handle 38. Thishandle may be grasped by the user to manually move the handle lever in aswinging motion about pivot pin 37 between its fully open position,shown in FIGURE 2, and its fully closed position, shown in FIGURE 3. Forthis purpose, a slot 39 is formed between the front wall of the rangebody and the top cooking surface 11 and the handle lever 36 extendsthrough this slot for manual manipulation.

The handle lever 36 is connected to the latching bolt 30 and both ofthese elements are further connected to the mounting bracket 25 by acompound pin and slot or cam follower connection which may best beunderstood by reference to FIGURE 3 in conjunction with FIGURE 5. A pin46 is provided to extend through a suitable opening in latching bolt 30so that the latching bolt may pivot with respect to the pin and may movelinearly with the pin. The lower end of pin 40 is captured within acam-shaped slot 41 formed in mounting bracket 25 and the upper end ofthe pin is captured in a complementary cam-shaped slot 41a formed inhandle lever 36. This arrangement forms a cam follower connectionbetween the handle lever 36 and the latching bolt 30. Cam-shaped slots41 and 41a are so shaped that pivotal or swinging movement of the handlelever 36 in a counterclockwise direction from the position shown inFIGURE 2 toward the position shown in FIGURE 3 will cause a clockwisepivotal or swinging movement of the latching bolt from the positionshown in FIGURE 2 toward the position shown in FIGURE 3. By the sametoken, a reverse movement of the handle lever will cause a reversemovement of the latching bolt. Moreover, cam-shaped slots 41 and 41aserve to pull the latching bolt 36 into the range cabinet in a linealmanner once the latching bolt 36 has engaged the keeper 32 of the door.This lineal movement serves to tightly clamp the door gasket 42 betweenthe door 14 and the door frame.

Firm seating of the handle lever and thus the remainder of the latchingmechanism in the open and closed positions is assisted by means of anovercenter spring 43 which is connected between a tab 44 formed on therearward portion of handle lever 36 and a second flange 45 formed alongone lateral edge of mounting bracket 25. Once the handle lever has beenmoved from either of its extreme positions past the center position ofthe spring 43, the spring tends to pull the handle lever to its otherextreme position. The positioning of the spring is such that it goesover-center as it passes beyond pivot pin 37.

As an important feature of this invention there is incorporated a doorsensor bar 46. The rearward end of the door sensor bar is pivotallymounted about pin 40 and is spaced from latching bolt 30 by an expandedcenter portion 47 of the pivot pin 40. A torsion spring 48 is connectedbetween a tab 49 formed on the latching bolt 30 and a tab 50 formed inthe door sensor bar. The torsion spring 48 functions to normally retainthe door sensor bar in a position where it overlies the hook portion 31of latching bolt 30 while leaving the door sensor bar 46 free to pivotaway from the hook portion 31. The door sensor bar is formed with a hookportion 51 which will engage the flange 26 adjacent one edge of the slot34 (as shown in FIGURE 4) to provide a stop means for preventingcomplete closure of the latch mechanism unless the door has first beenmoved to its closed position.

Combined with the latch mechanism 20, but not shown, is an electriccontrol circuit which is activated only when the latch mechanism is inits fully locked position. This electric control circuit controls theheat cleaning circuit for the oven so that it is not possible to raisethe oven temperature into the heat cleaning temperature range of betweenabout 750 F. and about 950 F. unless the latch mechanism 20 is fullyclosed. One modification would utilize an electric switch that would beactuated by the door sensor bar 46 once the bar has been deflected bythe door keeper 33. With such a switch, a person could not energize theheat cleaning cycle by manually moving the sensor bar, because once thehand is removed the sensor bar would disengage the switch.

Now for an explanation of the operation of the latch mechanism,attention is invited to FIGURE 4. It should be recognized that the ovendoor 14 is not present in its closed position. The handle lever 36 hasbeen moved in a swinging or pivotal movement from the position shown inFIGURE 2 to an intermediate position between the unlocked and lockedpositions of FIGURES 2 and 3 respectively, but this is as far as thelatch mechanism will move. The swinging motion has brought hook portion51 of the door sensor bar 46 into engagement with flange 26 adjacent theupper edge of slot 34 (as seen in FIGURE 4). Continued swinging movementof the handle lever 36 would cause a lineal movement of the latchingbolt 30 and door sensor bar 46 into the oven cabinet. This is due to thecam follower arrangement between the pin 40 and the cam-shaped slots 41and 41a. However, the engagement of hook portion 51 with flange 26prevents movement of door sensor bar 46 and thus prevents movement ofthe entire latching mechanism. It will be noted that over-center spring43 has not moved completely ovcr pin 37 so that the tension of theover-center spring tends to move the handle lever to the mechanism openposition shown in FIGURE 2. Thus, if the user releases the handle leverthe latch mechanism will be moved back to the unlocked position ofFIGURE 2.

By comparing FIGURE 4 with FIGURE 3, wherein the latch mechanism isshown in its fully closed position, you will notice that the outer endof door sensor bar 46 has been engaged by the edge of keeper 32 of ovendoor 14, which has prevented the hook portion 51 from swinging intoalignment with the edge of flange 26 of the mounting bracket 25. Becauseof this clearance between hook portion 51 and flange 26, the door sensorbar 46 was free to move linealy as movement of the handle lever wascontinued past the position shown in FIGURE 4 so that the handle leverand thus the entire latch mechanism was moved to its fully lockedposition.

Although I have described my invention of an improved door latchmechanism for an appliance such as an oven of a domestic range, it willreadily be apparent to those skilled in this art that such a latchmechanism would have general utility in other arts such as in adrop-door dishwasher and for the door of a microwave oven.

Modifications of this invention will occur to those skilled in the art,therefore, it is to be understood that this invention is not limited tothe particular embodiments disclosed, but that .it is intended to coverall modifications which are within the true spirit and scope of thisinvention.

What I claim as new and desire to secure by Letters Patent of the UnitedStates is:

1. A latch mechanism for locking a door, a door and a door frame wherethe door is hingedly mounted to the door frame along one edge thereof,said latch mechanism having a bracket which is supported in a positionadjacent one edge of said frame removed from the pivoted edge of thedoor, a latching bolt pivotally mounted on said bracket and including aportion on the free end thereof for mating engagement with the door, ahandle lever pivotally mounted on said bracket and pivotally connectedto said latching bolt so that swinging movement of said handle levercauses swinging movement of said latching bolt, a door sensor barpivotally supported on said bracket generally overlying the same,biasing means acting on said door sensor bar to cause swinging movementof said sensor bar .in response to swinging movement of said handlelever, and means defining an opening in the door frame through whichsaid latching bolt and door sensor bar move during swinging movementthereof, the movement of the handle lever from the open position towardthe closed position being interrupted if the door is not present in itsclosed position, the door sensor bar being positioned for lockinglyengaging a portion of the said opening defining means to cause saidinterruption and preventing further movement of either the latching boltor the sensor bar, while the presence of the door in its closed positionwould deflect the position of the door sensor bar with relation to thelatching bolt thereby disabling the door sensor bar and permitting thelatch mechanism to complete its travel to the fully closed position.

2. A latch mechanism adapted for locking a door, a door and a door framewhere the door is hingedly mounted to the door frame along one edgethereof, said latch mechanism having a bracket which is supported in aposition adjacent an edge of said frame removed from the pivoted edge ofthe door, a latching bolt pivotally mounted on said bracket andincluding a portion on the free end thereof for mating engagement withthe door, a handle lever pivotally mounted on said bracket and pivotallyconnected to said latching bolt so that swinging movement of said handlelever causes swinging movement of said latching bolt, a door sensor barpivotally supported on said bracket, biasing means acting on said doorsensor bar to cause a portion of it to overlie said free end of saidlatching bolt, and means in the door frame defining an opening throughwhich said latching bolt and said door sensor bar move during swingingmovement thereof, the movement of the handle lever from the openposition to the closed position being interrupted if the door is notpresent in its closed position, the door sensor bar being positioned forlockingly engaging a portion of the said opening defining means to causesaid interruption and preventing further closing movement of the handlelever, while the presence of the door in its closed position woulddeflect the door sensor bar from such locking engagement and permit thehandle lever to complete its travel to the fully closed position.

3. A latch mechanism adapted-for locking a door, a door and a door framewhere the door is hingedly mounted to the door frame along one edgethereof, said latch mechanism having a bracket which is supported in aposition adjacent an edge of said frame removed from the pivoted edge ofthe door, a latching bolt mounted on said bracket for combined swingingand lineal movement and including a portion on the free end thereof formating engagement with the door, a handle lever pivotally mounted onsaid bracket, a cam follower arrangement connecting said latching boltand said handle lever so that swinging movement of said handle leverfrom an open to a closed position causes first a swinging movement ofsaid latching bolt and then a substantially lineal movement toward thedoor frame, a door sensor bar pivotally supported on said bracket, aspring acting on said door sensor bar to cause a portion of it tooverlie said free end of said latching bolt, said door sensor barincluding a hook portion, and means in the door frame defining anopening through which said latching bolt and said door sensor bar movein response to swinging movement of said handle lever, the movement ofthe handle lever from the open position to the closed position beinginterrupted if the door is not present in its closed position, the hookportion of the door sensor bar being positioned for engaging the saidopening defining means to cause said interruption and preventing thesaid lineal movement of the latching bolt, while the presence of thedoor in its closed position would deflect the door sensor bar so thatthe bar clears the opening defining means and permits the handle leverto complete its travel to the fully closed position.

4. A latch mechanism adapted for locking a door, a door and a door framewhere the door is hingedly mounted to the door frame along one edgethereof, said latch mechanism having a bracket which is supported in aposi tion adjacent an edge of said frame removed from the pivoted edgeof the door, a latching bolt mounted on said bracket for combinedswinging and lineal movement and including a portion on the free endthereof for mating engagement with the door, a handle lever pivotallymounted on said bracket, a cam follower arrangement connecting saidlatching bolt and said handle lever so that swinging movement of saidhandle lever from an open position to a closed position causes first aswinging movement of said latching bolt and then a substantially linealmovement of said latching bolt toward the door frame, a door sensor bargenerally coinciding with the latching bolt and connected to said handlelever by said cam follower arrangement, a spring acting on said doorsensor bar to bias it for combined swinging and lineal movement inresponse to swinging movement of said handle lever, said door sensor barincluding a hook portion, the door frame defining an opening adjacentsaid bracket, said bracket including a flange overlying the opening inthe door frame, said flange defining an opening through which saidlatching bolt and door sensor bar move in response to swinging movementof said handle lever, the movement of the handle lever from the openposition to the closed position being interrupted substantially midwayof its travel if the door is not present in its closed position, thehook portion of the door sensor bar being positioned for engaging thesaid bracket flange and preventing the lineal movement of the latchingbolt to cause said interruption, while the presence of the door in itsclosed position would disable the door sensor bar so that the bar clearsthe bracket flange and the handle lever is permitted to complete itstravel to the fully closed position.

5. A latch mechanism adapted for locking a door, a door and a door framewhere the door is hingedly mounted to the door frame along one edgethereof, said latch mechanism having a bracket which is supported in aposition adjacent an edge of said frame removed from the pivoted edge ofthe door, a latching bolt pivotally mounted on said bracket andincluding a portion on the free end thereof for mating engagement withthe door, a handle lever pivotally mounted on said bracket and pivotallyconnected to said latching bolt so that swinging movement of said handlelever causes swinging movement of said latching bolt, a door sensor barpivotally supported on said bracket, a spring acting on said door sensorbar to cause a portion of it to coincide generally with said free end ofsaid latching bolt, the door frame defining an opening adjacent saidbracket, said bracket including a flange overlying the opening in thedoor frame, said flange defining an opening through which said latchingbolt and said door sensor bar move during movement thereof, the movementof the handle lever from the open position to the closed position beinginterrupted if the door is not present in its closed position, the doorsensor bar being positioned for lockingly engaging the bracket flangeand preventing further movement of the handle lever to cause saidinterruption, while the presence of the door in its closed positionwould cause a portion of the door to deflect the door sensor bar out ofcoincidence with the latching bolt thereby disabling the sensor bar andpermitting the handle lever to complete its travel to the fully closedposition.

6. A latch mechnaism adapted for locking a door, a door and a door frameWhere the door is hingedly mounted to the door frame along one edgethereof, said latch mechanism having a bracket which is supported in aposition adjacent an edge of said frame removed from the pivoted edge ofthe door, a latching bolt mounted on said bracket for combined swingingand lineal movement and including a portion on the free end of the boltfor mating engagement with the door, a handle lever pivotally mounted onsaid bracket, a cam follower arrangement connecting said latching boltand said handle lever so that swinging movement of said handle leverfrom an open position to a closed position causes first a swingingmovement of said latching bolt and then a substantially lineal movementof said latching bolt toward the door frame to pull the door in tight, adoor sensor bar pivotally supported on said bracket, a spring acting onsaid door sensor bar to cause a portion of it to overlie said free endof said latching bolt, said door sensor bar including a hook portion,the door frame defining an opening adjacent said bracket, said bracketincluding a flange overlying the opening in the door frame, said flangedefining an opening through which said latching bolt and said doorsensor bar move in response to swinging movement of said handle lever,the movement of the handle lever from the open position to the closedposition being interrupted if the door is not present in its closedposition, the hook portion of the door sensor bar being positioned forlockingly engaging the edge of the said opening in the bracket flangeand preventing further forward movement of the handle lever and hencethe lineal movement of the latching bolt to cause said interruption,while the presence of the door in its closed position would cause thedoor sensor bar to engage a portion of the door and the bar to bedeflected thereby to clear the bracket flange and permit the latchingbolt to complete its lineal movement into its fully closed position.

References Cited UNITED STATES PATENTS 10/1961 Jellies ZOO-61.62 6/1965Getman 292*111 X

